Hi Ross,
dspMixFX can be used along with another app such as Cubasis.
The app has been designed to control all DSP features of the hardware (such as the mixer and the effects) from the iPad. To give you one practical example, use the app to record your guitar in Cubasis using one of the guitar amp classics or record a vocal session using the sweet morph channel strip plus REV-X all provided by the UR.
Give the In-App help of the app a try to learn more about its features.
dspMixFX is available for iOS, Mac and PC.
Hope that helps,
Lars